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Title: Identifying the Active Surfaces of Electrochemically Tuned LiCoO 2 for Oxygen Evolution Reaction

Abstract

Identification of active sites for catalytic processes has both fundamental and technological implications for rational design of future catalysts. Herein, we study the active surfaces of layered lithium cobalt oxide (LCO) for the oxygen evolution reaction (OER) using the enhancement effect of electrochemical delithiation (De-LCO). Our theoretical results indicate that the most stable (0001) surface has a very large overpotential for OER independent of lithium content. In contrast, edge sites such as the nonpolar (1120) and polar (0112) surfaces are predicted to be highly active and dependent on (de)lithiation. The effect of lithium extraction from LCO on the surfaces and their OER activities can be understood by the increase of Co 4+ sites relative to Co 3+ and by the shift of active oxygen 2p states. Experimentally, it is demonstrated that LCO nanosheets, which dominantly expose the (0001) surface show negligible OER enhancement upon delithiation. However, a noticeable increase in OER activity (~0.1 V in overpotential shift at 10 mA cm –2) is observed for the LCO nanoparticles, where the basal plane is greatly diminished to expose the edge sites, consistent with the theoretical simulations. In addition, we find that the OER activity of De-LCO nanosheets can be improved ifmore » we adopt an acid etching method on LCO to create more active edge sites, which in turn provides a strong evidence for the theoretical indication.« less

Authors:
ORCiD logo [1];  [1];  [1];  [2];  [1];  [1];  [1];  [1];  [1]; ORCiD logo [1]; ORCiD logo [1];  [3];  [3]
  1. Stanford Univ., Stanford, CA (United States)
  2. Harvard Univ., Cambridge, MA (United States)
  3. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1368758
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 139; Journal Issue: 17; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Lu, Zhiyi, Chen, Guangxu, Li, Yanbin, Wang, Haotian, Xie, Jin, Liao, Lei, Liu, Chong, Liu, Yayuan, Wu, Tong, Li, Yuzhang, Luntz, Alan C., Bajdich, Michal, and Cui, Yi. Identifying the Active Surfaces of Electrochemically Tuned LiCoO2 for Oxygen Evolution Reaction. United States: N. p., 2017. Web. doi:10.1021/jacs.7b02622.
Lu, Zhiyi, Chen, Guangxu, Li, Yanbin, Wang, Haotian, Xie, Jin, Liao, Lei, Liu, Chong, Liu, Yayuan, Wu, Tong, Li, Yuzhang, Luntz, Alan C., Bajdich, Michal, & Cui, Yi. Identifying the Active Surfaces of Electrochemically Tuned LiCoO2 for Oxygen Evolution Reaction. United States. doi:10.1021/jacs.7b02622.
Lu, Zhiyi, Chen, Guangxu, Li, Yanbin, Wang, Haotian, Xie, Jin, Liao, Lei, Liu, Chong, Liu, Yayuan, Wu, Tong, Li, Yuzhang, Luntz, Alan C., Bajdich, Michal, and Cui, Yi. Tue . "Identifying the Active Surfaces of Electrochemically Tuned LiCoO2 for Oxygen Evolution Reaction". United States. doi:10.1021/jacs.7b02622. https://www.osti.gov/servlets/purl/1368758.
@article{osti_1368758,
title = {Identifying the Active Surfaces of Electrochemically Tuned LiCoO2 for Oxygen Evolution Reaction},
author = {Lu, Zhiyi and Chen, Guangxu and Li, Yanbin and Wang, Haotian and Xie, Jin and Liao, Lei and Liu, Chong and Liu, Yayuan and Wu, Tong and Li, Yuzhang and Luntz, Alan C. and Bajdich, Michal and Cui, Yi},
abstractNote = {Identification of active sites for catalytic processes has both fundamental and technological implications for rational design of future catalysts. Herein, we study the active surfaces of layered lithium cobalt oxide (LCO) for the oxygen evolution reaction (OER) using the enhancement effect of electrochemical delithiation (De-LCO). Our theoretical results indicate that the most stable (0001) surface has a very large overpotential for OER independent of lithium content. In contrast, edge sites such as the nonpolar (1120) and polar (0112) surfaces are predicted to be highly active and dependent on (de)lithiation. The effect of lithium extraction from LCO on the surfaces and their OER activities can be understood by the increase of Co4+ sites relative to Co3+ and by the shift of active oxygen 2p states. Experimentally, it is demonstrated that LCO nanosheets, which dominantly expose the (0001) surface show negligible OER enhancement upon delithiation. However, a noticeable increase in OER activity (~0.1 V in overpotential shift at 10 mA cm–2) is observed for the LCO nanoparticles, where the basal plane is greatly diminished to expose the edge sites, consistent with the theoretical simulations. In addition, we find that the OER activity of De-LCO nanosheets can be improved if we adopt an acid etching method on LCO to create more active edge sites, which in turn provides a strong evidence for the theoretical indication.},
doi = {10.1021/jacs.7b02622},
journal = {Journal of the American Chemical Society},
number = 17,
volume = 139,
place = {United States},
year = {Tue Apr 18 00:00:00 EDT 2017},
month = {Tue Apr 18 00:00:00 EDT 2017}
}

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